It has been known to mount a toner cartridge onto a toner box having a slit-like opening formed in a peripheral wall of a cylindrical cartridge container. A sealing film is removably attached to the slit-like opening. With this construction, the cartridge container can be set into a toner box after peeling the sealing film off. Another toner cartridge has been arranged such that a toner supply opening is formed in the top portion of a cartridge container and a covering member is provided to close the toner supply opening. The cartridge container is set into a toner box after peeling the sealing film off and then the toner cartridge is rotated by 180 degrees for the purpose of toner supply.
Such toner cartridges have experienced the problem of environmental pollution in that toner scatters when the toner cartridges are attached because it is necessary to open the toner cartridge before it is attached in the toner box. To solve this problem, there has been proposed a toner cartridge in Japanese Unexamined Patent Publication No. 58-224364. As shown in FIG. 14, the toner cartridge has an opening 2 formed in the lower portion of a substantially rectangular-parallelepiped cartridge container 1 for the purpose of toner supply. A sealing film 3 having a length about twice the width of the opening 2 is formed with one end fixed onto one longitudinal side edge of the opening 2. The other end of the sealing film 3a is turned back at an area facing the opening 2 and is fixed to the first end of the sealing film 3 or onto the one side edge of the opening 2 near the first end to form a loop. A covering member 4 is attached within the loop of the sealing film 3 so that the covering member 4 is slidable along the lower side of the cartridge container 1.
According to the toner cartridge of this type, when toner is to be supplied the covering member 4 is first positioned in the closed position shown by the solid line and then slid in the direction of the arrow A after the toner cartridge has been mounted onto a toner-receiving opening (not shown) of a toner box 5. In this condition, the covering member 4 peels the loop-like sealing film 3 off from the edge of the opening 2 with the movement of the covering member 4, so that the opening 2 is opened to supply toner into the toner box 5 from the cartridge container 1 without scattering.
When the toner cartridge 1 is to be removed from the toner box, the covering member 4 is first slid in the direction of the arrow B to close the opening 2. The covering member 4 acts on the loop-like sealing film 3 so that the sealing film 3 follows the movement of the covering member 4 to close the opening 2 securely. Accordingly, in removing the toner cartridge from the toner box, the problem that toner remaining within the toner cartridge scatters to the surroundings thereof can be effectively avoided.
In the aforementioned conventional toner cartridge, when the covering member 4 is slid in the direction of the arrow A to open the cartridge container 1, the end edge of the covering member 4 collides with the loop-like sealing film 3. Because the turnedback portion 3a of the loop-like sealing film 3 and the film attaching portion thereof at the peeling-off start point serve as static points, instantaneous hypertonic force T acts on the sealing film 2. Frictional resistance at the contacting portion between the end of the covering member 4 and the sealing film 3 increases according to the hypertonic force T. The movement resistance of the covering member 4 increases by the frictional resistance, and the operational force of the covering member 4 becomes high.
To overcome such a problem, the edge of the covering member 4 may be formed as an arc or be provided with pulleys 4a to reduce the frictional resistance at the contacting portion between the covering member 4 and the sealing film 3. Such structure, however, merely reduces the frictional resistance by the reduction of the frictional coefficient at the contacting portion on the side of the covering member 4. In short, the problem is not completely solved and other problems arise in that the edge portion of the covering member 4 and the attaching points of the sealing film 3 are complicated in construction. Consequently, the toner cartridge cannot be produced at a low cost, which is necesary since the toner cartridge must be disposable.